[oilpan] Completely move HTMLFormControlElement's hierarchy to the managed heap

Source/core/html/HTMLInputElement.h

Index: Source/core/html/HTMLInputElement.h
diff --git a/Source/core/html/HTMLInputElement.h b/Source/core/html/HTMLInputElement.h
index 7adc4401b8b65b928e99e790e1782af7478a3499..eaed56fa953025a123c10d664c861a24fbf2c811 100644
--- a/Source/core/html/HTMLInputElement.h
+++ b/Source/core/html/HTMLInputElement.h
@@ -45,12 +45,12 @@ struct DateTimeChooserParameters;
 
 class HTMLInputElement : public HTMLTextFormControlElement {
 public:
-    static PassRefPtr<HTMLInputElement> create(const QualifiedName&, Document*, HTMLFormElement*, bool createdByParser);
+    static Result<HTMLInputElement> create(const QualifiedName&, Document*, HTMLFormElement*, bool createdByParser);
     virtual ~HTMLInputElement();
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(webkitspeechchange);
 
-    virtual HTMLInputElement* toInputElement() { return this; }
+    virtual Result<HTMLInputElement> toInputElement() { return Handle<HTMLInputElement>(this); }
 
     virtual bool shouldAutocomplete() const;
 
@@ -205,7 +205,7 @@ public:
 
     Vector<String> acceptMIMETypes();
     Vector<String> acceptFileExtensions();
-    String accept() const;
+    String acceptAttribute() const;
     String alt() const;
 
     void setSize(unsigned);
@@ -248,7 +248,7 @@ public:
     void listAttributeTargetChanged();
 #endif
 
-    HTMLInputElement* checkedRadioButtonForGroup() const;
+    Result<HTMLInputElement> checkedRadioButtonForGroup() const;
     bool isInRequiredRadioButtonGroup();
 
     // Functions for InputType classes.
@@ -298,6 +298,8 @@ public:
     bool setupDateTimeChooserParameters(DateTimeChooserParameters&);
     virtual void reportMemoryUsage(MemoryObjectInfo*) const OVERRIDE;
 
+    virtual void acceptHeapVisitor(Visitor*) const OVERRIDE;
+
 protected:
     HTMLInputElement(const QualifiedName&, Document*, HTMLFormElement*, bool createdByParser);